1. Field of the Invention
The present invention relates to a clean air apparatus used in a manufacturing process of semiconductor elements, and an apparatus for processing semiconductors using the clean air apparatus. 2. Description of the Related Art
Regarding an apparatus for manufacturing semiconductors, the density of semiconductor elements has recently been increased and fine dusts attached to the semiconductor elements in the manufacturing process make the semiconductor elements defective. As a result, the yield is reduced. Therefore, it is important to prevent such dusts. In particular, as the integration density increases, smaller dusts must be taken into consideration. In order to solve this problem, the semiconductor manufacturing apparatus, such as a heat treating apparatus, etching apparatus, spatter apparatus, etc. is installed in a clean room. In this room, the vertical flow of clean air is formed as follows: after passing air sent from an air blowing apparatus to a ceiling, the air is blown toward the floor through a filter installed in the ceiling, and the air is exhausted from the floor.
However, since the content volume of the clean room is limited and more production lines are required to be provided, semiconductor wafers are processed in the clean room, and the most of semiconductor processing apparatuses are arranged in a maintenance room which has comparatively low cleanliness and is separated from the clean room by means of a partition wall.
This type of the apparatus, i.e. through-the-wall type semiconductor processing apparatus comprises an opening/closing door for carrying wafers to be treated in/out of the main body or housing of the apparatus, in front of an apparatus positioned in the clean room. The door is opened from the clean room side, and a carrier housing wears is carried in and out of the mounting portion provided in the apparatus.
The pressure in the clean room is generally higher than the pressure in the maintenance room. The flow of air from the clean room side to the maintenance room side through the body of the apparatus is formed by the differential pressure, when the door is opened in the case of carrying the wafer carrier in the apparatus.
Although the inside of the clean room is always clean, a workman in the clean room is the source of generating dusts. Therefore, when this workman carries the carrier housing wafers in the semiconductor processing apparatus, the dusts are dispersed and carried by means of the flow of air blown into the apparatus from the clean room side, so that the yield of the semiconductor elements is reduced.
In order to settle this problem, Published Unexamined Japanese Patent Application (PUJPA) No. 61-2602 discloses technique wherein clean air circulates in the semiconductor processing apparatus. Moreover, PUJPA No. 59-100517 discloses technique wherein an opening portion of the apparatus is covered with the flow of the carrier gas so as to control the entering of the outer air.
In the case that clean air is circulated in the former processing apparatus, the inside of the apparatus can be kept clean when the apparatus is closed and the clean air is normally circulated in the apparatus. However, when a part of the apparatus is opened, e.g. when an opening/closing door is opened in the case of carrying the wafers in/out of the apparatus and the carrier housing the wafers is carried in the apparatus, the dusts dispersed from the workman of the clean room side are entered in the apparatus, and the yield of the semiconductor elements is reduced.
In the case of providing air shower at the opening/closing door for carrying the carrier in the latter technique disclosed in PUJPA No. 59-100517, it is difficult to form a laminar flow air curtain between the clean room and the inside of the apparatus, and moreover, the dusts, etc. enter into the apparatus from the clean room side, so that the yield of the semiconductor elements is reduced.